Fundamentals of modern theory of correlated electronic tunneling have been elaborated as early as several years ago. A worldwide interest displayed in this new domain of physics and technology is concerned with the broadest potentialities and prospects offered by further research in single-electron phenomena and development of new promising technologies based thereon.
From the standpoint of physics the meaning of that phenomenon resides in electronic correlations due to Coulomb electrostatic interaction of electrons in diverse micro- and nano-scale structures. On the other hand, single-electronics is a route towards development of such electronic device that the operating concept of which is based on information coding by lone electrons.
One state-of-the-art three-lead (three-electrode) semiconductor device (U.S. Pat. No. 4,286,275) is known to comprise a combination of the base region having a physical size of the order of the length of a free path of the majority carrier, the emitter region which establishes a first barrier relative to the base region and featuring the barrier width sufficient for quantum-mechanical tunneling, and the collector base forming a lower barrier With respect to the base region than the first barrier and featuring the barrier width high enough to inhibit quantum-mechanical tunneling and ohmic contact with each of the emitter, base, and collector regions.
The three-lead (three-electrode) semiconductor device under discussion featuring a changeover time of about 10-12 s and offering a negative dynamic resistance, is created from a thin barrier region in the emitter section having a barrier height exceeding that in a wider barrier region of the collector section which separated by the base section having a width comparable with the length of the length of a free path of the majority carrier. The operation of the device is based on quantum-mechanical tunneling as the principal mechanism of electrical conduction through the base region to the collector region.
Field of application: amplification, changing-over, and establishing dynamic resistance.
Specific features: the collector barrier has such a width that tunneling current flowing therethrough is but negligible. Emitter-base junction: main conductance due to quantum-mechanical tunneling.
Dimensions: base--100 .ANG.;
width of emitter barrier--80 .ANG.;
width of collector barrier--120 to 150 .ANG..
The device discussed before is based on quantum-mechanical tunneling as the principal mechanism of electrical conduction from the emitter region to the base region, and of transferring hot major carriers through the base region to the collector region.
One more state-of-the-art three-lead (three-electrode) semiconductor device based on quantum wells (U.S. Pat. No. 4,912,531) is known to function as a MOS transistor. This means that in a general sense the three leads of the device may be considered as a source, a pass, and a drain. The output terminal communicates, by virtue of the tunneling effect, with a number of parallel circuits of quantum wells, each of which is adequately small for the energy levels therein to quantize discretely. In each of such pit circuits the second pit is connected to a second common conductor, while the first pit is electronically connected to a first common conductor.
A method for making GaAs-based electric elements of nanoelectronics and computer facilities with an insulating molecular Langmuir-Blodgett layer (U.S. Pat. No. 5,079,179) is known to comprise formation of an insulating layer appearing as Langmuir-Blodgett (LB) film interposed between a GaAs substrate and the conducting terminal.
The thickness of said layer is variable so as to set the functional characteristics of the device. The polar head group of a molecule of LB-film is so selected as to passivate the surface state of GaAs used as the substrate. There are found some preferable acid- and amino-groups or the polar head of molecules. It has been established that the LB-layer increases the height of the control barrier for a field-effect transistor and passivates broken bonds and surface flaws in the GaAs substrate, which makes possible inversion-mode operation. The method is applicable only for preparing macroscopic devices, i.e., field-effect transistor and diodes.
One of the most promising methods for making functional elements of nanoelectronics is a method for making an electronic device involving organic materials (EP #0469243), which provides for establishing of electronic devices, wherein electron current flows through an electrically conducting monomolecular or multi-monomolecular film.
Said method for making an electronic device involving organic material consists in establishing a first and a second electrodes on a substrate provided with an insulating film on its surface; etching out the insulating film using the first and second electrodes as a mask; forming a monomolecular or multi-monomolecular film, containing electrolytically polymerizable groups directly or indirectly on the substrate surface which functions as a third electrode; applying a voltage across the first and the second electrodes for the electrolytically polymerizable groups to polymerize; and withdrawing the third electrode from the substrate.
The aforediscussed method for making an organic electronic device is instrumental in forming a monomolecular or a multi-monomolecular film comprising electrolytically polymerizable groups, using the Langmuir-Blodgett technique. In addition, a possibility is provided for developing an electrode device involving an organic material, wherein formation of a monomolecular or a multi-monomolecular film containing polymerizable groups, involves the procedure of forming at least one layer of a monomolecular film by chemical adsorption of a silane-base surfactant, containing polymerizable unsaturated groups, from a nonaqueous organic solvent onto the substrate surface, followed by polymerization of the resultant film.
Furthermore, according to said method for making an electronic device, formation on the substrate surface of at least one layer of a monomolecular film containing electrolytically polymerizable unsaturated groups is followed by electrolytic polymerization of said unsaturated groups by applying an electric voltage across the first electrode and the second electrode in order to establish connection between the first and second electrodes through electrically conducting conjugated groups, while said silane-based surfactant is in fact a chemical substance containing a chlorosilyl group at its end.
An indispensable prerequisite for carrying said method into effect is that the monomolecular or multi-monomolecular films should contain electrically conducting conjugated groups, such as a polythienylene group, so that bonding between the first and second electrodes be effected by said polythienylene groups.
The known method for making an organic electronic device is featured by forming said first and second electrodes on a solid-state substrate, by an electrolytically polymerized monomolecular or multi-monomolecular layer interposed between said electrodes, and by establishing a third control electrode connected directly or indirectly to said monomolecular or multi-monomolecular layer, as well as to the first and second electrodes. Applying a voltage between the third and second electrodes allows of control over the electric current flowing between the first and second electrodes and depending on a change in the applied voltage.
In view of the foregoing, an inference can be made that the known method is instrumental in making electronic devices involving organic materials and utilizing the electron current flowing through an electrically conducting monomolecular or multi-monomolecular organic film.
The region through which electric current flows is established by conjugated links present in an organic material, specifically in said organic monomolecular or multi-monomolecular organic film, said links resulting from electrolytic polymerization of said film, whereby high functional capabilities and reduced overall dimensions of the device are attained.
It is due to the use of the chemical adsorption or LB-technique along with electrolytic polymerization that polymers having electrically conducting conjugated bonds may very efficiently be made on the concepts of self-organization, for electrically connecting two electrodes, with the result that highly perfect electronic organic devices may be obtained.